Pervasive computing devices such as PDAs (personal digital assistants), pocket PCs (personal computers), tablet PCs, and smart camera/PDA phones have steadily increased in popularity. Chip technology has made it possible for these devices to be small but functionally powerful. However, due to the decreased size of the devices, there is little to no room for a keyboard, and most include a tiny display.
The addition of a virtual keyboard image for input and/or a virtual display for user output has been proposed as a way to attempt to improve the usability and portability of these pervasive computing devices. For example, U.S. Pat. No. 6,323,942 discloses a virtual keyboard. Further, U.S. Pat. No. 6,266,048 discloses a virtual display/keyboard for a PDA, which provides a solution to the limitations caused by the size of the pervasive computing device. A keyboard image is projected on a surface close to the user and a display image is projected on the same surface between the virtual keyboard image and the projecting device. While this increases the size of both the keyboard image and the display, the placement of both images on the same surface is uncomfortable for the user because the user must look downward to read the user output display. This is not the customary placement for a computer screen and a user would have to become accustomed to the new placement. The system of U.S. Pat. No. 6,266,048 also uses a first projector for the keyboard image, and a second projector for the display.
The above mentioned approaches fail to provide a system that produces an optimal ergonomic and economic virtual input and output. Thus, a need exists for an improved virtual input and output system which overcomes these and other limitations.